Dimerization cyanoanthracene

For instance, head-head photodimers are predicted from the crystal structures of 9-cyanoanthracene and 9-anthraldehyde, but the head-tail isomer is produced. Craig and Sarti-Fantoni and later others found that photoreactions of 9-cyanoanthracene and 9-anthraldehyde take place at defect sites [96,215], Systematic photochemical and crystallographic studies by Schmidt and co-workers uncovered many cases of substituted anthracenes which behave in an unexpected fashion (Scheme 40) [216,217]. Examples shown in Scheme 40 clearly illustrate that, unlike cinnamic acid derivatives, the stereochemistry of the product dimer from anthracenes cannot be predicted on the basis of crystal packing. An example from the laboratories of Venkatesan is noteworthy in this context [218], Irradiation of crystals of 7-... 

Albini et al. reported that the cross-dimerization of 9-cyanoanthracene with substituted naphthalenes and anthracenes takes place through a significantly polar intermediates and is affected by solvents and substituents [156], The combination of 9-cyanoanthracene and unsubstituted anthracene in CH3CN gave the best result (Scheme 31). Photoirradiation of 9-cyanoanthracene with 1-methylnaphthalene,... 

The dimerization of thioformylketene was investigated by B3LYP and G3MP2B3 methods. The 4 + 4-pathway has the lowest energy barrier and calculations suggest that the reaction is pseudopericyclic.231 The stereospecific intramolecular 4 + 4-cycloaddition reaction between cyclohexadiene iron tricarbonyl complex and appended dienes (198) generates cyclooctadiene tricyclic adducts (199) (Scheme 56).232 The first example of an asymmetric intermolecular 4 + 4-photocycloaddition reaction in solution between 9-cyanoanthracene and chiral 2-methoxy-l-naphthamides has been reported. The frozen chirality is effectively transferred to the optically active product.233... 

Theocaris, C. R. and Jones, W. (1984). The thermally induced phase transition of crystalline 9-cyanoanthracene dimer A single crystal study. J. Chem. Soc., Chem. Commun., 369-84. [234, 237]... 

Quenching Excimers and Exciplexes.—By measurements of decay times and fluorescence anisotropy of pyrene and the excimer in cellulose acetate films it has been found that the medium consists of spaces where small pyrene molecules have considerable freedom, Dissado and Walmsley have developed a complete theory of excimer formation and exciton-induced lattice distortion in crystals. Reference is made to data on 9-cyanoanthracene. The spectroscopy of chemically linked dimers of l,3-(l,l -dinaphthyl)propane in a... 

Interest in the monomerization of anthracene photodimers continues the head-to-tail dimer (290) (see p. 361) produced by irradiation of 9-cyanoanthracene has been investigated by two groups. " From results of differential scanning calorimetry and emission spectroscopy of cleaved surfaces of partially monomerized single crystals, it is suggested that the first exothermic peak (and the subsequent ones) arises from monomer crystallization in the photodimer host matrix. " Theocharis and Jones have also examined this retroprocess and using single crystal X-ray techniques they have shown that the first step in the solid-state thermal monomerization of this dimer is a... 

When after formation of photoproduct at one of the two sites the crystal was heated and cooled the photoreaction was reversed. We were able to conclude with the help of the packing calculations of sec. 3.2 and other experimental results that those impurity molecules that reacted could not be those that replaced anthracenes in the regular lattice, but must be at dislocations or regions of abnormal packing, where the host and guest were in face-to-face positions. The reaction is thus belongs to the class of the photodimerizations of anthracene, and 9-cyanoanthracene, not of dimers formed topochemically in the normal lattice. 

Cyanoanthracene photodimer [33998-38-8] M 406.4, dec to monomer above 147. Purify the dimer by dissolving it in the minimum amount of CHCI3 followed by addition of EtOH at 5° [Ebied et al. 7 Chem Soc, Faraday Trans 1 75 1111 1979, Ebied et al. J Ghent Soc, Faraday Trans 1 76 2170 7980]. 

Cyanoanthracene has a 3-type crystal structure but produces a head-to-tail photodimer. Unlike cinnamic acids and their derivatives, the stereochemistry of the photoproduct dimer from anthracenes cannot often be predicted on the basis of their crystal packing [78]. 9-Methoxyanthracene has a photostable y-type crystal structure. 9-CNA host crystals doped with 9-MeOA form a solid solution, which upon irradiation yield a heterodimer (3> = 0.12). A reaction mechanism via an exciplex is proposed. The exciplex fluorescence was observed [32] ... 

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